Add an AuthServer_Private constructor

This fixes the Postgres SELECT ERROR AuthVault.cpp logspam by ensuring ageNodeId is zero (invalid) rather than some random stack value that might not play nicely as a signed 32-bit integer.
Change message broadcasts to be nonblocking
Merge pull request #72 from Hoikas/nonblocking-propagate

Concurrency Improvement
Merge remote-tracking branch 'huru/master'